Modular implant for combination hip replacement with intramedullary rod

Abstract

This invention provides a device and treatment method for replacing the hip (in either a hemiarthroplasty or total hip arthroplasty), which protects the remainder of the femur from fracture. Such a device is highly applicable to the treatment of patients with current or impending fractures of the femur, particularly those with metastatic bone cancer, where there is concern for current or future metastatic disease of the femoral neck or head, which would necessitate hip replacement. The implant consists of a two-piece arrangement with a separate femoral component and a securing, intermedullary rod/nail that is received in a locking arrangement by a longitudinal fenestration of the femoral component.

What is claimed is: 
     
       1. An implant for use in hip replacement comprising:
 a femoral component comprising a longitudinal fenestration including an upper cranial region that is disposed atop an intermediary tapered interconnection region, and a distal elongated region that is disposed below the intermediary tapered interconnection region; and 
 a securing, intermedullary rod constructed of three continuous regions, the three continuous regions comprising: 
 
       an upper region having a diameter shaped and sized to define a close engagement with the femoral component at the upper cranial region, 
       an intermediary tapered region received by the femoral component in a locking arrangement through engagement at the intermediary tapered interconnection region, and 
       a distal region that engages with the distal elongated region. 
     
     
       2. The implant as set forth in  claim 1  wherein the femoral component defines a shaft adapted to seat within a cavity formed in a proximal end of a patient's femur. 
     
     
       3. The implant as set forth in  claim 2  wherein the rod includes at least one securing fastener at a distal end thereof. 
     
     
       4. The implant as set forth in  claim 2  wherein the femoral component includes an arm that carries a ball joint. 
     
     
       5. The implant as set forth in  claim 2  wherein at least one of the femoral component and the rod are arranged to be cemented into the cavity. 
     
     
       6. A method for hip replacement comprising the steps of:
 (a) preparing a proximal end of a patient's femur to define a cavity for receiving an implant having a ball joint; 
 (b) inserting, into the cavity, a first component of the implant; and 
 (c) inserting a second component into the cavity in engagement with the first component proximate to the proximal end at an upper region shaped and sized to define a close engagement therebetween, at a distal region, and at an intermediary tapered interconnection region disposed between the upper region and the distal region to define a locking relationship. 
 
     
     
       7. The method as set forth in  claim 6  wherein the first component is a femoral component having the ball joint and a shaft with a fenestration, and the second component is an intermedullary rod that engages the fenestration in a locking relationship. 
     
     
       8. The method as set forth in  claim 7  wherein the fenestration and a proximal end of the rod each define engaging tapered segments that are sized and arranged to interengage in the locking relationship. 
     
     
       9. The method as set forth in  claim 6  wherein the first component is an intermedullary rod, and the second component is a femoral component having the ball joint and a shaft with a fenestration, wherein a proximal end of the rod engages the fenestration. 
     
     
       10. The method as set forth in  claim 6  wherein either the first component or the second component is an intermedullary rod, and further comprising the step of securing the intermedullary rod into the cavity with at least one of fastener(s) and cement. 
     
     
       11. The implant as set forth in  claim 1 , wherein the cranial region is sized to define a close engagement with the upper region of the intermedullary rod and the distal elongated region is narrower than the cranial region and sized to closely conform to a portion of the distal region of the intermedullary rod. 
     
     
       12. The implant as set forth in  claim 1 , wherein the cranial region and the distal elongated region are each substantially uniform in diameter. 
     
     
       13. The method as set forth in  claim 6  wherein the upper region and the distal region are each distinctly uniform in diameter. 
     
     
       14. An implant for use in hip replacement comprising:
 a femoral component comprising a ball joint receiving end, and an elongated shaft extending from the ball joint receiving end and configured for insertion into a femur of a patient, the elongated shaft including a longitudinal fenestration comprising an upper cranial region disposed above an intermediary tapered interconnection region, and a distal region disposed below the intermediary tapered interconnection region; and 
 a securing, intermedullary rod comprising a femur-proximal portion shaped to engage with the femoral component at each of the upper cranial region, the intermediary tapered interconnection region, and the distal region, the rod further comprising a femur-distal portion configured to pass through the longitudinal fenestration, wherein the intermedullary rod is received by the femoral component in a locking arrangement through engagement of the intermediary tapered interconnection region of the longitudinal fenestration with a corresponding intermediary tapered region of the intermedullary rod.